fix(control): keep npm pack JSON on stdout

Author: andrescera

.omo/evidence/task-modem-stack-pack-json-stdout-fix.md

@@ -0,0 +1,51 @@
+# npm pack JSON stdout fix
+
+## Root cause
+
+`npm pack ./control --json > pack.json` redirects the parent shell's stdout for
+the entire command, including the `prepack` child process. `prepack` runs
+`bun run build`, and `control/scripts/build.ts` wrote its informational
+`built 7 public entries into dist/` message with `console.log`. That message
+was therefore prepended to npm's JSON array and made `pack.json` unparsable.
+
+The build message is progress information, not a machine-readable result. It
+now uses `console.error`, leaving stdout available for JSON-producing callers.
+
+## Before
+
+Command, from the repository root:
+
+```text
+$ npm pack ./control --json > /tmp/pack-test-before.json 2>/tmp/pack-test-before.stderr
+$ node -p "require('/tmp/pack-test-before.json')[0].filename"
+SyntaxError: /tmp/pack-test-before.json: Unexpected token 'b', "built 7 pu"... is not valid JSON
+```
+
+The captured stdout began:
+
+```text
+built 7 public entries into dist/
+[
+  {
+```
+
+The command itself exited 0; the subsequent JSON consumer failed, matching the
+release workflow failure.
+
+## Fix and after
+
+`control/scripts/build.ts` line 150 changed from `console.log(...)` to
+`console.error(...)`. A complete search of `control/scripts/build.ts` found no
+other `console.log` calls. The neighboring tarball and consumer scripts use
+their logs as human-facing CLI output and do not produce the npm JSON stream.
+
+```text
+$ npm pack ./control --json > /tmp/pack-test-after.json 2>/tmp/pack-test-after.stderr
+$ node -p "require('/tmp/pack-test-after.json')[0].filename"
+ceralive-modem-control-1.1.0.tgz
+$ node -p "require('/tmp/pack-test-after.json')[0].integrity"
+sha512-8Q7Qa0fFS8d42C0xcaWlOGswwE/3fuMk8+PHXCfED9DOhCP3LRPmrvdIyK47NUNaLZEcffN2z/BVTOekILAVfA==
+```
+
+After the fix, the JSON file starts with `[` and the build progress line is in
+`/tmp/pack-test-after.stderr`.

control/scripts/build.ts

@@ -147,4 +147,4 @@ if (tsc.exitCode !== 0) {
 await fullySpecifyEmit();
 await verify();
 
-console.log(`built ${PUBLIC_ENTRIES.length} public entries into dist/`);
+console.error(`built ${PUBLIC_ENTRIES.length} public entries into dist/`);